An injection nozzle is described in U.S. Pat. No. 3,926,219. However, it has the disadvantage that the pin of the nozzle needle cannot be produced with a diameter of less than 0.8 mm for reasons of production technology. The use of a nozzle with a pin has been considered necessary in order to avoid "split conveyance." The term "split conveyance" means that the component which is supplied in a metered fashion is simultaneously conveyed partially into the mixing chamber and partially into the return pipe. The ratio of the conveying streams therefore becomes uncontrollable and perfect mixing cannot be achieved.
As there is a trend towards mixheads for the production of small parts, smaller nozzle openings must be used in order to reduce the throughputs.
The object to be achieved is to find an injection nozzle whose nozzle opening can be substantially smaller in design than hitherto but which ensures that the conveyed component is either supplied completely to the mixing chamber or passes completely into the return.